Nebulizer Aperture Plate Drive Frequency Control and Monitoring

1. A nebulizer comprising: a vibrating aperture plate configured to be driven by an actuator; and an aperture plate drive circuit having a controller in communication with the actuator, wherein the controller is configured to: perform a scan measuring a value of an electrical parameter at each of a plurality of measuring points, each measuring point being associated with a different drive frequency at which the drive circuit is operated; and determine, based on the values of the electrical parameter measured at the plurality of measuring points, end-of-dose of the nebulizer, wherein the controller is configured to perform the scan at each of two or more measuring points with different drive frequencies and determine end-of-dose of the nebulizer based at least in part on a maximum differential of the electrical parameter.

2. The nebulizer of claim 1, wherein the controller is further configured to perform the scan at least in part in response to measurements made during a prior scan and wherein the prior scan has fewer than five measuring points.

3. The nebulizer of claim 2, wherein the prior scan is a short scan and wherein the short scan is performed at regular intervals.

4. The nebulizer of claim 3, wherein the regular intervals are sub-second.

5. The nebulizer of claim 1, wherein the scan has in the range of 5 to 300 measuring points.

6. The nebulizer of claim 5, wherein the scan has in the range of 100 to 300 measuring points.

7. The nebulizer of claim 1, wherein the electrical parameter is an aperture plate drive current.

8. The nebulizer of claim 1, wherein the controller is further configured to determine end-of-dose of the nebulizer by comparing the maximum differential of the electrical parameter to a threshold differential and wherein the maximum differential being above the threshold differential indicates end-of-dose of the nebulizer.

9. The nebulizer of claim 1, wherein the electrical parameter is an impedance of the aperture plate.

10. The nebulizer of claim 1, wherein the controller is further configured to determine, based at least in part on the values of the electrical parameter measured at the plurality of measuring points, the maximum differential of the electrical parameter.

11. A method of operation of a nebulizer comprising a vibrating aperture plate driven by an actuator in communication with an aperture plate drive circuit having a controller, wherein the method comprises: performing a scan measuring a value of an electrical parameter at each of a plurality of measuring points, each measuring point being associated with a different drive frequency at which the drive circuit is operated; and determining, based on the values of the electrical parameter measured at the plurality of measuring points end-of-dose of the nebulizer, wherein the scan measures the electrical parameter at each of two or more measuring points with different drive frequencies and wherein determining end-of-dose of the nebulizer is based at least in part on a maximum differential of the electrical parameter.

12. The method of claim 11, wherein the scan is performed at least in part in response to measurements made during a prior scan and wherein the prior scan has fewer than five measuring points.

13. The method of claim 12, wherein the prior scan is a short scan and wherein the short scan is performed at regular intervals.

14. The method of claim 13, wherein the regular intervals are sub-second.

15. The method of claim 11, wherein the scan has in the range of 5 to 300 measuring points.

16. The method of claim 15, wherein the scan has in the range of 100 to 300 measuring points.

17. The method of claim 11, wherein the electrical parameter is an aperture plate drive current.

18. The method of claim 11, wherein the electrical parameter is an impedance of the aperture plate.

19. The method of claim 11, wherein determining end-of-dose of the nebulizer further comprises comparing the maximum differential of the electrical parameter to a threshold differential and wherein the maximum differential being above the threshold differential indicates end-of-dose of the nebulizer.

20. The method of claim 11, further comprising determining, based at least in part on the values of the electrical parameter measured at the plurality of measuring points, the maximum differential of the electrical parameter.